Support screenshots of HDR content

Previously screenshots always rendered to either an SDR or a wide gamut
colorspace. For screenshotting HDR content, this is only appropriate
when the resulting screenshot (a) never leaves the device and (b) the
relevant code has workarounds for the display to appropriately handle
its luminance range.

HDR screenshots will now have two paths:
* A standard path for rendering to HLG. HLG was chosen because the OOTF
  shape is less hand-wavey than PQ's, does not require metadata, and
  bands less at 8-bits of color.
* A special path for "display-native" screenshots. This is for
  use-cases like screen rotation where there are stricter color accuracy
  requirements for round-tripping.

Skia already encodes the resulting screenshot by supplying an HLG CICP
alongside a backwards-compatible transfer function, so it's only
sufficient to change how SurfaceFlinger renders.

Bug: 242324609
Bug: 276812775
Test: screencap binary
Test: rotation animation
Test: swiping in Recents
Change-Id: Ic9edb92391d3beb38d076fba8f15e3fdcc2b8f50

1 files changed, 3 insertions, 1 deletions

diff --git a/services/surfaceflinger/RegionSamplingThread.cpp b/services/surfaceflinger/RegionSamplingThread.cpp
index 531d277ffc..8f658d5a09 100644
--- a/services/surfaceflinger/RegionSamplingThread.cpp
+++ b/services/surfaceflinger/RegionSamplingThread.cpp
@@ -277,10 +277,12 @@ void RegionSamplingThread::captureSample() {
 
     const Rect sampledBounds = sampleRegion.bounds();
     constexpr bool kUseIdentityTransform = false;
+    constexpr bool kHintForSeamlessTransition = false;
 
     SurfaceFlinger::RenderAreaFuture renderAreaFuture = ftl::defer([=] {
         return DisplayRenderArea::create(displayWeak, sampledBounds, sampledBounds.getSize(),
-                                         ui::Dataspace::V0_SRGB, kUseIdentityTransform);
+                                         ui::Dataspace::V0_SRGB, kUseIdentityTransform,
+                                         kHintForSeamlessTransition);
     });
 
     std::unordered_set<sp<IRegionSamplingListener>, SpHash<IRegionSamplingListener>> listeners;